NEW YORK -- In an about-face, U.S. Rep. Chris Collins is ending his re-election bid days after the Republican congressman from New York was charged with insider trading, while his Democratic challenger is calling on him to resign immediately.

Collins released a statement Saturday morning saying he will suspend his campaign and finish the rest of his term. Collins was indicted Wednesday on charges he passed inside information about a biotechnology company to family members so they could profit from illicit trades. He had said later that day he would remain on the ballot despite the indictment and fight the charges.

But Collins reversed himself Saturday. "I have decided that it is in the best interests of the constituents of NY-27, the Republican Party and President Donald Trump's agenda for me to suspend my campaign for re-election to Congress," his statement said.

He went on to say he will fill out his term and "continue to fight the meritless charges brought against me." He has denied any wrongdoing.

Collins' decision to end his re-election bid appeared to boost Democrats' chances of taking in a solidly Republican district, but the announcement left unanswered questions including how Collins' name could be removed from the ballot.

The Democratic candidate in the November election, Nate McMurray, said in a statement on Saturday that Collins has no choice but to quit Congress, given the seriousness of the allegations against him.

It is "a continuing disgrace that both parties have not said, with one clear voice, 'Resign, Mr. Collins, and do it today,"' said McMurray, a supervisor for the town of Grand Island in western New York.

Wednesday's indictment charges Collins and two others, including his son, with conspiracy, wire fraud and other counts.

Prosecutors say the charges relate to a scheme to gain insider information about a biotechnology company headquartered in Sydney, Australia, with offices in Auckland, New Zealand.

It is unclear whether Collins' name can be removed from the November ballot at this point and whether Republican Party officials will be able to nominate another candidate for the seat.

Under New York state election law, Collins' name could be taken off the ballot under certain narrowly defined circumstances that include death, disqualification or being nominated for a different office such as a county clerkship.

Jessica Proud, a spokeswoman for the New York state Republican Party, said party officials are weighing their options. She said no decision has been made about a possible replacement for Collins on the ballot -- if they are able to replace him.

Stefan Mychajliw, the Erie County comptroller, released a statement putting his name forward for the ballot spot and said he hoped to earn the support of county Republican officials in the district.

The district spans an area between the Rochester and Buffalo suburbs and is considering the most Republican-leaning district in New York. The race had not been considered competitive by many observers, including those predicting a "blue wave" that gives Democrats control of the House.

The area backed Trump over Hillary Clinton by nearly 25 percentage points in 2016, when Collins beat his Democratic challenger by more than 2-1.

Collins was an early supporter of Trump's presidential campaign and has been one of Trump's most ardent defenders. In his statement Saturday, Collins warned of Democrats winning the House in the midterm elections "and then launching impeachment proceedings against President Trump."

House Democratic Leader Nancy Pelosi said Saturday that Collins should resign immediately.

"No person is above the law, not the president or his first supporter in Congress," Pelosi said. "This insufficient and overdue announcement does little to drain the toxic cesspool of self-enrichment, special interest deals and corruption that has proliferated in Washington under GOP control. "